1. Field of the Invention
This invention relates to viscous liquid dispensers, and, in particular, to a viscous liquid dispenser having a yieldable dispensing lever arm and arrangement for varying the volume of viscous liquid expelled.
2. Description of the Prior Art
Devices for the dispensing of a viscous liquid or paste-like product are known in the art. These devices may, for example, use a roller moving over a resilient tube that is connected to a viscous liquid reservoir to expel viscous liquid from the tube. As the roller advances, the resilient tube is progressively compressed between the roller and a suitably disposed back-up block. Examples of such prior art devices are U.S. Pat. No. 2,113,002, issued to Hefti, and U.S. Pat. No. 3,006,832, issued to Rosetti.
Alternatively, other prior art dispensing devices may utilize contact members which are first moved to constrict a portion of a resilient tube. Then, the contact member is forced into compressive contact with the resilient tube to cause viscous liquid to be expelled therefrom. Examples of the latter type viscous liquid dispenser are U.S. Pat. No. 3,741,439, issued to Vehrs, and U.S. Pat. No. 3,870,201, issued to Asplund. It is usually a problem of prior art devices of any type to have an unsightly and unsanitary coagulated mass of viscous liquid remaining at the orifice of the resilient tube left from previous dispensations of viscous liquid therefrom.
Both of the last-mentioned patents provide a contact member which is brought into compressive contact with a resilient tube extending from a viscous liquid reservoir to expell viscous liquid from the resilient tube. However, neither of these last-mentioned patents provide any mode of controlling the volume of liquid expelled during the actuation stroke of the apparatus. Also, neither of the last mentioned patents utilize a resiliently yieldable actuating lever arm to bring the compressing member into compressive contact with the resilient tube. Yet further, neither of these last-mentioned patents disclose suction means for drawing excess viscous liquid back into the resilient tube to prevent the coagulation of excess viscious liquid.
It would be advantageous to provide a viscous liquid dispensing apparatus having a suitable mechanism provided therein for varying the magnitude of viscous liquid expelled during the actuation stroke thereof. It would be of further advantage to provide a viscous liquid dispensing device utilizing a yieldable dispensing lever arm, actuation of which initially contacts a portion of a rigid dispensing block into constricting contact with the resilient tube and further actuation thereof causes yieldable deformation of the lever arm to compress a portion of the resilient tube below the constriction between the dispensing block and a compression surface on an oppositely disposed back-up block.
It is advantageous to provide a viscous liquid dispensing device including suitable suction means for drawing excess viscous liquid into the resilient tube to thereby prevent the unsightly and unsanitary coagulation of viscous liquid common in prior art dispensing apparatus. Thus, it is of further advantage to provide suction means in the form of a long-throw ball check valve such that cessation of an actuating force on the yieldable dispensing lever arm permits a spring bias element to overcome compressive forces within the viscous liquid to urge the ball to the closed position and to generate a suction force to draw viscous liquid into the downstream terminus of the resilient tube and thereby prevent dripping and coagulation of the viscous liquid product.